The present invention relates to an apparatus for removing impurities from effluent waste gas streams, and in particular to an apparatus for removing fluorinated and chlorinated compounds from effluent waste gas streams from semiconductor etch and deposition processes.
Fluorinated and chlorinated compounds are used in semiconductor etch and deposition processes. These compounds are suspected of causing global warming and environment pollution and contamination, and should be removed.
Scrubbing apparatuses made by STMI EcoSys Corporation have been widely used by semiconductor manufacturers. Among these scrubbing apparatuses, the ES Vector Series Models (for example, the ES-100 model) uses plastic packing therein to let effluent gas streams from semiconductor etch and deposition processes contact with a liquid (for example, water) so that the impurities in the effluent gas streams can be absorbed into the water and removed. However, the plastic packing needs replacement after a period of treatment time and bubbles form in the plastic packing when the scrubbing apparatus is used. These disadvantages limit the total flow rate (indicating the efficiency of the scrubbing apparatus) of the waste gas streams through the ES-100 type scrubbing apparatus to only 2831 liters/m3.
Incineration has been shown an effective means of removing the impurities in the effluent gas streams from semiconductor etch and deposition processes. The Delatech of the CDO series of the ATMI EcoSys Corporation incinerates waste gas streams at a temperature of 850xc2x0 C. However, the total flow rate of the waste gas streams using the Delatch is only about 300 liters/m3. And chlorine gas produced in the incineration is a flammable gas which is explosive and hazardous to both personnel and equipment because of its corrosivity and in some cases toxicity.
It is therefore an object of the invention to provide an apparatus for removing impurities from waste gas streams that can eliminate the above disadvantages of the prior art.
The above object of the invention is attained by providing a plurality of water films formed by a spraying device, each of which are formed vertically and spaced apart from each other in a treatment chamber in a manner that waste gas streams are sucked through the plurality of water films by a blower, and the impurities contained therein are mixed with water to form a mixture while simultaneously the waste gas streams are humidified. The mixture flows downward and is removed and the humidified waste gas stream is sucked out from the treatment chamber.
Most impurities, such as fluorinated and chlorinated compounds, contained in the waste gas streams are almost dissolved in water. The mixture is flowed into and stored in the tank so as to be further treated, and the amount of the mixture is detected by a set of sensors disposed in the tank. Therefore, water consumed in the semiconductor etch and deposition process can be supplied in time.
According to an aspect of the invention, each water film is formed by a spraying device disposed in the treatment chamber, which includes a pipe having a nozzle from which the water is sprayed out and a plate disposed on the opposite side of the nozzle. The sprayed-out water impinges on the plate to form the water film.
According to another aspect of the invention, the apparatus for removing impurities from waste gas stream also includes a dehumidifying device. The dehumidifying device includes a chamber having a plurality of perforated buffer plates disposed along the longitudinal axis thereof and a plurality of filtering plates disposed along the longitudinal axis thereof. The perforated buffer plates stabilize the humidified waste gas streams that pass through the plates. The filtering plates remove the solid impurities in the humidified waste gas streams and condense the humidified waste gas streams so as to dehumidify them.